A hot air balloon, or montgolfier, is composed of two main parts:
First the envelope, made of nylon fabric, (maximum heating temperature 110°C or 125°C) or polyester fabric (up to 149° C). The hot air’s ascending force (and so the weight and number of passengers it can lift) depend on the volume of the envelope. The registration number is displayed on the envelope. At its top is the parachute vent, designed to release hot air whenever needed in order to stop an ascent or initiate a descent.
The second part is the basket, usually made of woven wicker or rattan. It may have a triangular or rectangular shape. The weaving is either horizontal or vertical. Wicker was chosen for its light weight and flexibility. Its ability to change shape temporarily makes it shockproof. Gas tanks are mounted in the basket (liquid propane, freezing temperature -44°C) to fuel the burner.
A frame is set up on the basket to hang the gas burner above the pilot’s head, under the envelope’s mouth. Pipes carry the gas from the bottles to the burner(s). The basket is linked to the envelope by suspension cables. They can be metal cables or Kevlar ropes. There are 3 or 4 suspension sets depending on the basket’s shape (triangular or rectangular). We currently use a FireFly balloon, designed in the USA but registered in France. The envelope is made of 18 assembled gores with a total volume of 2,200 cubic meters (77,000 cu.ft). It’s made of polyester, with a maximum heating temperature of 149°C (300° F). Three Kevlar suspension cables link the envelope to the basket; which is triangular and woven with a vertical weave. Thus, it is less vulnerable to the friction on the ground and can easily absorb any shock. It has got 4 aluminium 10 gallon Worthington gas tanks (about 40 litres each) fuelling the Mirage Burner. All these components are inspected annually in compliance with current air safety standards.